If a player with Exp. Share on a benched Pokemon has discarded their Active Pokemon and its attached energy due to KO from an attack and already promoted a new Active Pokemon, have they missed the opportunity to use Exp. Share?
Promoting a new Active Pokemon takes place after the knockout, so at that point it would be too late to use Exp. Share.
Source: TPCi Rules Team (2016-10-27)

Relevant cards

Note: All applicable cards may not be listed below.
XY5_128